Sintering of powders from fiberglass recycling

Sintering is a typical process for metal powders which can be effectively agglomerated by a solid state diffusion mechanism. Polymer powders are less sensible to this kind of mechanism because of the lower molecular mobility. Anyway, such applications have been mentioned about sintering of thermoplastic powders in the scientific literature. In this study, sintering has been used for the first time to agglomerate thermoset powders coming from recycling of fiberglass. This way, two interesting results have been obtained. First of all, new products have been produced by recycling fiberglass without any addition of virgin resin or linking agent. Moreover, it has been shown that sintering can lead to very high thickness products which are very difficult to obtain by typical molding processes because of shrinkage or frozen stresses. In order to show the feasibility of this new process, some powders have been collected from the waste of industrial partners. These powders have been molded without the addition of any other material so as to produce small plates or thick bricks. In such cases, a polyester coating was also added to improve the surface quality of the brick. Several samples have been extracted from these products and tested to evaluate the mechanical performances of the recycled plates. Results are very promising in terms of process easiness and part properties. A density about 1 g/cm3 has been obtained with a flexural modulus about 1 GPa and a flexural strength up to 20 MPa.